﻿using KouDai.Core.ViewModel;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using KouDai.Metro.Helper;
using System.Diagnostics;

// The Items Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234233

namespace KouDai.Metro.Views
{
    /// <summary>
    /// A page that displays a collection of item previews.  In the Split Application this page
    /// is used to display and select one of the available groups.
    /// </summary>
    public sealed partial class ImageWallItemsPage : KouDai.Metro.Common.LayoutAwarePage
    {

        private ImageWallItemsViewModel _viewModel;

        public ImageWallItemsPage()
        {
            this.InitializeComponent();
            _viewModel = this.DataContext as ImageWallItemsViewModel;

            this.Loaded += ImageWallItemsPage_Loaded;
        }

        void ImageWallItemsPage_Loaded(object sender, RoutedEventArgs e)
        {
            ScrollViewer scrollViewer = SuperVisualTreeHelper.FindVisualChildByName<ScrollViewer>(itemGridView, "ScrollViewer");
            ScrollBar scrollBar = SuperVisualTreeHelper.FindVisualChildByName<ScrollBar>(scrollViewer, "HorizontalScrollBar");

            scrollBar.ValueChanged += OnScrollBarValueChanged;
        }

        async void OnScrollBarValueChanged(object sender, RangeBaseValueChangedEventArgs e)
        {
            if (e.NewValue == (sender as ScrollBar).Maximum)
            {
                Debug.WriteLine("加载....");
                await _viewModel.GetItems();
            }
        }

        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="navigationParameter">The parameter value passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
        /// </param>
        /// <param name="pageState">A dictionary of state preserved by this page during an earlier
        /// session.  This will be null the first time a page is visited.</param>
        protected override async void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
        {
            // TODO: Assign a bindable collection of items to this.DefaultViewModel["Items"]
            await _viewModel.GetItems();
        }
    }
}
